Improved electrical properties of p-type CuGaO2 semiconductor thin films through Mg and Zn doping

Abstract Undoped, Mg-doped, and Zn-doped p-type CuGaO 2 semiconductor thin films were deposited on quartz substrates by a sol-gel spin coating method. The effects of the two dopants (Mg and Zn) on the structural features and electrical properties of the CuGaO 2 -based thin films were investigated. The doping concentration was maintained at 1 at% in the impurity doping precursor solutions. X-ray diffraction (XRD) results showed that only the undoped CuGaO 2 thin films had a single delafossite phase; Mg- and Zn-doped thin films exhibited mixed CuGaO 2 and CuGa 2 O 4 phases. Scanning probe microscopy (SPM) images showed that the surfaces of the dense CuGaO 2 -based thin films exhibited obviously granular structures. Hall measurements confirmed that the three oxide semiconductor thin films had p-type conductivity. Compared with undoped CuGaO 2 thin films, the Mg- and Zn-doped thin films exhibited improvements in electrical properties, and the Zn-doped thin films had the highest mean carrier concentration of 3.49×10 16 cm −3 . In addition, three kinds of n-Si/p-CuGaO 2 -based thin film heterojunctions were fabricated and their current-voltage (I-V) characteristics were examinated. It was found that the n-Si/p-CuGaO 2 :Zn heterojunction exhibited a distinct rectifying I-V characteristic with a forward turn-on voltage of 2.9 V.